The organic electroluminescent devices (hereinafter, “electroluminescent” is referred to merely as “EL”) are emitting devices using the principle that a phosphor or fluorescent substance emits light by an energy of recombination between holes injected from an anode and electrons injected from a cathode upon application of an electric field thereto. Since C. W. Tang, et al., of Kodak Company have reported low-voltage drive organic EL devices of a laminated type (C. W. Tang and S. A. Vanslyke, “Applied Physics Letters”, Vol. 51, p. 913, 1987, etc.), there have been made intense studies concerning organic EL devices made of organic materials. The organic EL devices reported by Tang, et al., include a luminescent layer made of tris(8-hydroxyquinolinol)aluminum and a hole transport layer made of a triphenyl diamine derivative. The laminated structure of these devices provides advantages such as enhanced injection efficiency of holes into the luminescent layer, enhanced production efficiency of excitons that are produced by blocking electrons injected from a cathode and recombining the electrons with holes, and confinement of the excitons produced within the luminescent layer. As the structure of such organic EL devices, there are well known a two-layer structure including a hole transport (injection) layer and an electron transport luminescent layer, a three-layer structure including a hole transport (injection) layer, a luminescent layer and an electron transport (injection) layer, etc. In these organic EL devices of a laminated type, various structures and methods for production thereof have been proposed in order to enhance an efficiency of recombination between holes and electrons injected.
In addition, as the luminescent materials for the above devices, there are known chelate complexes such as tris(8-quinolinolato) aluminum complexes, coumarin derivatives, tetraphenyl butadiene derivatives, bis-styryl arylene derivatives and oxadiazole derivatives. It has been reported that these luminescent materials emit blue to red light in a visible range, and it is therefore expected to apply these luminescent materials to production of color display devices (for example, Japanese Patent Application Laid-open Nos. Hei 8(1996)-239655, Hei 7(1995)-138561 and Hei 3(1991)-200889, etc.).
However, there exist few blue emitting luminescent materials capable of providing highly-reliable and stable blue light-emitting devices. In general, the conventional blue emitting luminescent materials are easy to crystallize. For example, diphenyl anthracene shows a high crystallinity nevertheless their high fluorescent quantum yield. Therefore, the use of such a compound as a luminescent material has failed to provide devices exhibiting a high luminous efficiency and a high reliability (C. Adachi, et al., “Applied Phys. Lett.”, 56, 799 (1990)).